Improvement in apparatus and processes for drying wood and other substances



T. A. BOWLING.- Apporatus and Process for Drying Wood and otherSubstances. o

No. 217,273. Patented July 8, 1879.1

ullll u N-PETEIIS, PNOTO-UTBOG1AFHFJ1 WASHINGTON. D. C.

UNITED S AT PATENT OFFICE.

THOMAS A.nowL1Ne,oF NEW YORK, N. Y.

IMPROVEMENT IN APPARATUS 'AND PROCESSES FOR DRYING WOOD AND OTHERSUBSTANCES.

Specification forming part of Letters Patent No. 217,273, dated July 8,1879; application filed March 19, 1879.

To all whom it may concern: I Be itknown that I, THOMAS ,A. Downriver,of the city, county, and State of New York,

' have invented certain new and useful Improvements in Apparatus andProcesses for Dryiii'g Wood and other Substances, of whichthe followingis a specification.

1' use strong vessels of boiler-iron, and cylind'er-shaped, providedwith a movable cover,

with steam-tight fittings, such as are employed for similar purposes inthe 'arts, \vhiehvessels, for convenience, I designate as digeste'is,the dimensions of which should be according to the general work to beperformed. 1

For convenienceand economy it is well to have two or more of suchvessels placed side by side, and connected by proper pipes andstopcocks. Coils of iron pipes are secured around or along the inside ofthe digester-shell, with their ends projecting outside for externalconnections or'the digesters may be made double- ,shelled, with anannular space for steam or hot water between them.

Stopcocks, blow-off and safety valves, press-- ure and water gages, andthermometers should pressure and hot, it becomes condensed, as ifpressed in a mold, in which condition it is dried and cooled, and madesecure from subsequent alteration when exposed to the external air.

During the process I draw off the vaporized matters by'a condensingoperation in condenser-conduits, thatare sealed from the air by atrap-vessel and dip-pipe. (Shown in the drawing.)

A shows the digester, that has acoil of steampipe close around theinside of its shell, the ends of this pipe projecting through thedigester at h h. B represents the forcing airpump, with its pipe,stop-cock, and cheekvalve g, connecting it to A, 0 being the drivin gsteam-cylinder. Branch pipes, with proper 'stopco cks, leadfroin h auditto a cold-water hydrant or supply for cooling purposes.

"Dis a cold-water tank, to which j is a supply, and i a waste, pipe. anshow a condensii'ig-coil in the tank, one leg being connected with thebottom of the digester, with a stopcock at m, While the lower leg isattached to a sealing trap-vessel, E, the inside of which is providedwith a combined float and valve, a shown in section at F.

A branch or vapor pipe is seen-at l, the upper end beingnnited with thetop part of the digester, and the lower-end joined with the coil mlandprovided witlra stop-cock. A pet testing-cock andpipe are shown at It. 1

. The outlet-pipe of the scaling-vessel E is designed to dip into theflui'dof a receivingvessel, (not shown,) to exclude'the air from it.

The operation with my apparatus is as follows: The-wood or othersubstance being pr'operly packed and the digesterblosed steamtight,steam from a boiler is admitted to the coil-pipes by thejunct-ion it,its return being by h to a trap-vessel. The digester is then charged bythe pump with air to any desired high pressure. The air havingno escapeand the pressure being fixed, the pump is stopped. This dense and heatedair quickly converts the moisture into steam, the pressure from whichcompensates for a consequent reduction of, the airpressure and reductionresulting from the action of the condenser, which automatically drawsaway the vapors by the pipe 1 into its coil n, in which there will be apartial vacuum. The condensed fluid will pass into the sealingtrap-vessel E until itlifts the float and valve, which will liberate thefluid into a receiving-vessel. (Not shown.) Then they will again drop totheir first position, which automatic action will continue until thevapors are all drawn out and the wood dried, and the pet-cock indicatesdry air in the digeste-r. Steam should then be shut off from theheating-coil, and substituted cold water turned through it by means of abranch pipe connecting with h, to cool the interior of the vessel, theair-pressure being kept up by work ing the pump wheh necessary therefor.When the temperature has been cooled down by the r Water to, say, 150Fahrenheit, the air-press, are is liberated by the blow-off, and thedigester may be opened and the charge removed.

By such means the wood will be gradually, rapidly, and'thoroughlyseasoned and cooled, so that neither cracking nor checking can occur, asis liable when the'wood is not cooled undersnch pressure maintained tothe last. Moreover, wood seasoned by my process has a novel texture andappearance, by reason of its compactness of fiber, and consequentimprovement in color.

Other contrivances may be substituted for the particular trap vesseldescribed, other means for heating the interior of the digester, and thesteam admitted through the coil-pipe may be superheated by anintermediate furnace; .but the supply of dry air under pressure isindispensable, as also the free liberation and sealed condensation ofthe vaporized fluids.

I am aware of a closed vessel for burning coffee, which is provided witha coil of pipe in a heating-chamber. A constant current of air is forcedthrough this pipe, and is heated in its transit, but passing from thepipe freely into and circulating through the coffee from the bottom ofthe vessel to the top, into which an outlet-pipe prolonged into acondensingcoil is fixed, the pipe being still further prolonged to asecond condensingand receiving vessel for the products of condensation.A waste-pipe is fixed into the top of this third vessel for theair-outlet, by which it escapes constantly and freely to the atmosphere,interrupted only by a weighted valve placed in the pipe between thedigester and condenser to check the air-flow at that point.

It would seem unnecessary to point out the great distinction in thefunctional duties of the two inventions, and-the impossibility ofeffecting my desired result in wood with the coffee apparatus. I heatthe contents of the drying-vessel, and obtain pressure therein in such amanner as to control and govern each step separately. I confine iny heatand seal up my pressure, retaining both from first to last; and mypressure once obtained needs very little work afterward from the pump. I

cause the air to enter directly into the operating-chamber, where it isstored and heated under high pressure, to quickly and effectuallypenetrate the wood, and eventually compress its fibers. I dry thematerial and the air surrounding itsimultaneously, by drawing offgradually the disengaged vapors into an automatic sealing andcondensingapparatus, which operates byboth vacuum and pressure, .While Iprevent the air of the drying-chamber from escaping into the atmosphereat all.

I am also aware that in a lumber-drying apparatus a continuous circuitof air has been maintained by a blast apparatus, a condenser and heaterbeing used in the circuit, and the condensed water discharged freelyinto the outer air. I disclaim the invention of such a combination.

What I claim, and desire to secure by Letters Patent, in my improvementfor drying wood and other substances, is

1. The following elements in combination: a sealed vessel oroperating-chamber, provided with an internal coilof pipeforsteam-heating, or with other heating contrivance, an air-pump forhigh pressure,'and a condensing apparatus for vaporized matters, allarranged substantially in the manner and for the purposes set forth.

2. An automatic condensing and sealing apparatus, in combination with anair-forcing pump and heating contrivance, and operating chamber, fortreating wood and other substances, for the purpose and in the mannerdescribed.

3. The described process of drying wood and other substances, bysubjecting them to heat in a closed chamber while subjected to confinedair-pressure, and gradually drawing off therefrom the cooled vapors by acondensing apparatus, and cooling the treated substance while under suchconstant air-pressure, substantially as described.

THOS. A. BOWLING.

Witnesses JOHN HARDMAN, A. J. KENDALL.

